SUMMARY On MS Windows 10, Okular cannot save .okular files for edited DjVu and epub files. STEPS TO REPRODUCE 1. Open DjVu or epub file 2. Make an annotation 3. Attempt to save the document as a .okular file OBSERVED RESULT An error appears, such as this: File could not be saved in 'C:/Users/___/AppData/Local/Temp/okular.kKTmaU'. Try to save it to another location. EXPECTED RESULT A .okular document archive should be created. SOFTWARE/OS VERSIONS Windows: 10 build 1903 ADDITIONAL INFORMATION Okular is most likely trying to overwrite a temporary file which it is already using, which is forbidden by NTFS.
By the way I have tested this with Windows builds 164 and 591.
*** This bug has been marked as a duplicate of bug 431717 ***